Q: Which of the following is the correct mole-to-mole ratio for the reaction $$2\mathrm{C}_8\mathrm{H}_{18}(l) + 25\mathrm{O}_2(g) \rightarrow 16\mathrm{CO}_2(g) + 18\mathrm{H}_2\mathrm{O}(g)$$?

$$2\text{ mol } \mathrm{C}_8\mathrm{H}_{18} : 25\text{ mol } \mathrm{O}_2 : 16\text{ mol } \mathrm{CO}_2 : 18\text{ mol } \mathrm{H}_2\mathrm{O}$$

Q: Which of the following is the correct formula for the percent yield of a chemical reaction?

$$\text{Percent yield} = \dfrac{\text{actual yield}}{\text{theoretical yield}} \times 100\%$$

Question 1

Which statement best describes the Law of Conservation of Mass as it applies to chemical reactions?

Accepted Answer

The total mass of reactants must equal the total mass of products.

Question 2

What is the balanced chemical equation for the combustion of methane?

Accepted Answer

$$\mathrm{CH}_4(g) + 2\mathrm{O}_2(g) \rightarrow \mathrm{CO}_2(g) + 2\mathrm{H}_2\mathrm{O}(g)$$

Question 3

In the reaction $$4\mathrm{FeCO}_3(s) + \mathrm{O}_2(g) \rightarrow 2\mathrm{Fe}_2\mathrm{O}_3(s) + 4\mathrm{CO}_2(g)$$, how many oxygen atoms are present on the right-hand side?

Accepted Answer

12

Question 4

Which of the following must always be the same on both sides of a balanced chemical equation?

Accepted Answer

The number of atoms of each kind

Question 5

A student burns 22.0 moles of octane ($$\mathrm{C}_8\mathrm{H}_{18}) $$according to the equation $$2\mathrm{C}_8\mathrm{H}_{18}(l) + 25\mathrm{O}_2(g) \rightarrow 16\mathrm{CO}_2(g) + 18\mathrm{H}_2\mathrm{O}(g). $$How many moles of water are produced?

Accepted Answer

198 moles

Question 6

Which of the following best describes a combustion reaction?

Accepted Answer

A reaction in which a substance combines with oxygen to form one or more oxygen-containing compounds and emits heat.

Question 7

If 42.5 g of magnesium reacts with 33.8 g of oxygen according to $$2\mathrm{Mg}(s) + \mathrm{O}_2(g) \rightarrow 2\mathrm{MgO}(s)$$, which is the limiting reactant?

Accepted Answer

Oxygen

Question 8

What is the percent yield if 195 g NaBr was produced when 84.7 g of sodium was combined with 175.0 g of bromine, and the theoretical yield is 206 g?

Accepted Answer

$$94.7\%$$

Question 9

Which of the following is the correct mole-to-mole ratio for the reaction $$2\mathrm{C}_8\mathrm{H}_{18}(l) + 25\mathrm{O}_2(g) \rightarrow 16\mathrm{CO}_2(g) + 18\mathrm{H}_2\mathrm{O}(g)$$?

Accepted Answer

$$2	ext{ mol } \mathrm{C}_8\mathrm{H}_{18} : 25	ext{ mol } \mathrm{O}_2 : 16	ext{ mol } \mathrm{CO}_2 : 18	ext{ mol } \mathrm{H}_2\mathrm{O}$$

Question 10

During photosynthesis, plants convert carbon dioxide and water into glucose according to $$6\mathrm{CO}_2(g) + 6\mathrm{H}_2\mathrm{O}(l) \rightarrow 6\mathrm{O}_2(g) + \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6(aq). If a $$plant consumes 37.8 g of $$\mathrm{CO}_2$$, what mass of glucose can be synthesized?

Accepted Answer

25.8 g

Question 11

Which of the following is the correct formula for the percent yield of a chemical reaction?

Accepted Answer

$$	ext{Percent yield} = \dfrac{	ext{actual yield}}{	ext{theoretical yield}} 	imes 100\%$$

Question 12

In a reaction mixture containing 5 mol $$\mathrm{NO}_2$$ and 1 mol $$\mathrm{H}_2\mathrm{O}$$, which is the reactant in excess after the reaction $$3\mathrm{NO}_2(g) + \mathrm{H}_2\mathrm{O}(l) \rightarrow 2\mathrm{HNO}_3(l) + \mathrm{NO}(g) is $$complete?

Accepted Answer

2 mol $$\mathrm{NO}_2$$

Question 13

Which of the following is true about balancing chemical equations?

Accepted Answer

Coefficients are changed to balance the equation, not the subscripts.

Question 14

Which of the following reactions is a correct example of an alkali metal reacting with water?

Accepted Answer

$$2\mathrm{M}(s) + 2\mathrm{H}_2\mathrm{O}(l) \rightarrow 2\mathrm{M}^+(aq) + 2\mathrm{OH}^-(aq) + \mathrm{H}_2(g)$$

Question 15

Which of the following is a correct balanced equation for the reaction between aqueous strontium chloride and aqueous lithium phosphate to form solid strontium phosphate and aqueous lithium chloride?

Accepted Answer

$$3\mathrm{SrCl}_2(aq) + 2\mathrm{Li}_3\mathrm{PO}_4(aq) \rightarrow \mathrm{Sr}_3(\mathrm{PO}_4)_2(s) + 6\mathrm{LiCl}(aq)$$

Question 16

Which of the following is the correct sequence for solving a mass-to-mass stoichiometry problem?

Accepted Answer

Mass A $$\rightarrow$$ moles A $$\rightarrow$$ moles B $$\rightarrow$$ mass B

Question 17

Which of the following reactions is a correct example of a halogen reacting with hydrogen?

Accepted Answer

$$\mathrm{H}_2(g) + X_2$ \rightarrow 2\mathrm{HX}(g)$$

Chemical Reactions and Chemical Quantities: Chapter 4 Study Notes

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